There are varieties of wheelchairs, most of the conventional wheelchairs do not have seat adjusting mechanisms, recently to enhance convenience and comfort in use, some seats are designed with up-down adjustable or lean adjustable mechanism. However, the current common seen wheelchair seat adjusting mechanism moves the seat up and down by a simple linking rod with actuator, e.g. U.S. Pat. No. 5,924,720, the seat is up-down adjustable with a 4 linking-rod mechanism composed of continuous 2 linking rod in between the cart frame and the seat frame together with a linear motion actuator, this commonly applied mechanism takes a lot of space which makes driving difficult and inconvenient in transportation. There are some other kinds of well known wheelchairs equip with seat up-down adjusting mechanisms, but there is nothing like this invention which is a mechanism designed to minimize space and is hidden in a way of nice figure.
In addition to the function of seat up-down adjustment, the main mechanism of this invention can be extended in design to have a function of seat lean adjustment. A current common seen wheelchair has the function of seat lean adjustment, i.e. U.S. Pat. No. 6,776,430, which has a linking rod and an actuator between the cart frame and the seat frame; a guide rail which rising gradually and extending to the front is installed on the cart frame; a slide which installed on the seat frame which slides along the guide, when the actuator pulls back, the rear side of the seat frame is pulled forward and raised, then the seat frame is leaned. However, it does not have the function to control the seat up and down; furthermore, the guide rail is rising and extending to the front, when the seat is leaned, the height of the seat is increased, which causes unstable, uncomfortable and dangerous to the rider.